Analytische Chemie
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In various kinds of radiography, deficient transmission imaging may occur due to backlighting inside the detector itself arising from light or radiation scattering. The related intensity mismatches barely disturb the high resolution contrast, but its long range nature results in reduced attenuation levels which are often disregarded. Based on X-ray observations and an empirical formalism, a procedure is developed for a first order correction of detector backlighting. A backlighting factor is modeled as a function of the relative detector coverage by the sample projection. Different cases of sample transmission are regarded at different backlight factors and detector coverage. The additional intensity of backlighting may strongly affect the values of materials’ attenuation up to a few 10%. The presented scenario provides a comfortable procedure for corrections of X-ray or neutron transmission imaging data.
X-ray backscatter imaging is a well established NDT technique to inspect complex objects using only a single-sided access. In difference to conventional transmission X-ray radiography, the X-ray backscatter imaging utilizes the scattered radiation caused by the Compton scattering effect. In order to achieve high backscatter intensities from a test object, it is necessary to optimize the backscatter system parameters namely the angle between source and slit camera, the slit collimator system, the shielding between source and scatter camera, and the type of detector. In addition, the scatter phenomena in to the investigated object need to be understood.
In this contribution, we present a Monte Carlo model McRay which considers all relevant single and multiple interactions of photons and electrons. This model can be used to simulate back scatter techniques. It allows not only calculating the scatter image for a given experimental setup but also registering the spectrum of the detected scattered photons. Both aspects are important to understand the imaging process, to interpret the results, and to optimize the backscatter camera investigated here. Additionally experimental results will be presented and compared with simulations.
X-ray backscatter imaging is a well established NDT technique to inspect complex objects using only a single-sided access. In difference to conventional transmission X-ray radiography, the X-ray backscatter imaging utilizes the scattered radiation caused by the Compton scattering effect. In order to achieve high backscatter intensities from a test object, it is necessary to optimize the backscatter system parameters namely the angle between source and slit camera, the slit collimator system, the shielding between source and scatter camera, and the type of detector. In addition, the scatter phenomena in to the investigated object need to be understood.
In this contribution, we present a Monte Carlo model McRay which considers all relevant single and multiple interactions of photons and electrons. This model can be used to simulate back scatter techniques. It allows not only calculating the scatter image for a given experimental setup but also registering the spectrum of the detected scattered photons. Both aspects are important to understand the imaging process, to interpret the results, and to optimize the backscatter camera investigated here. Additionally experimental results will be presented and compared with simulations.